Front-side Illumination Research Articles

High performance Bi-facial dye sensitized solar cells developed using MXenes assisted novel photoelectrode design

A new device architecture of bi-facial dye sensitized solar cell (DSSC) is designed, fabricated by use of novel photoelectrode design contains MXenes. The developed bi-facial DSSC witnessed higher power conversion efficiency (PCE) of 12.82 % with short-circuit current density (JSC) of 27.46 mA/cm2. The DSSC revealed 9.74 % of PCE by front side illumination and 4.57 % by back side illuminations. The results motivated to develop mini-module of series connected 12 test cells, which results in 13.34 % of PCE.

A composite electrocatalytic poly(3,4-ethylenedioxythiophene) film incorporated with silver nanowires for bifacial dye-sensitized solar cells

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a superior electrocatalyst for dye-sensitized solar cells (DSSCs). The porous PEDOT film, however, lacks directional conduction paths, resulting in slower electron transfer and lower cell efficiency. In this study, silver nanowires (Ag NWs) are incorporated into a PEDOT film to construct a PEDOT-coated Ag NW composite film, wherein the Ag NWs serve as highways for charge transport. The composite film is constructed by spreading Ag NWs on tin-doped indium oxide (ITO) glass via a three-step process (dip coating, brush painting, and thermal compression), followed by coating a PEDOT film via electropolymerization. The DSSC catalyzed by the PEDOT-coated Ag NW exhibited an efficiency of 9.22 % under one-sun illumination, outperforming platinum (9.09 % efficiency) and PEDOT (8.33 % efficiency) by increasing the short-circuit current density. Chemical state analyses were performed to determine the interactions between the Ag NWs and PEDOT. Impedance measurements and quantum chemical calculations were conducted to rationalize the functionality of the PEDOT-coated Ag NWs. Owing to its high transparency, the resulting DSSC achieves an efficiency of 6.74 % under rear illumination, demonstrating its high feasibility as a bifacial DSSC. The DSSC also exhibited high efficiencies ranging from 14.05 % to 19.69 % under front-side illumination at low intensities of 300–1000 lux.

Fresnel Diffraction Model for Laser Dazzling Spots of Complementary Metal Oxide Semiconductor Cameras.

Laser dazzling on complementary metal oxide semiconductor (CMOS) image sensors is an effective method in optoelectronic countermeasures. However, previous research mainly focused on the laser dazzling under far fields, with limited studies on situations that the far-field conditions were not satisfied. In this paper, we established a Fresnel diffraction model of laser dazzling on a CMOS by combining experiments and simulations. We calculated that the laser power density and the area of saturated pixels on the detector exhibit a linear relationship with a slope of 0.64 in a log-log plot. In the experiment, we found that the back side illumination (BSI-CMOS) matched the simulations, with an error margin of 3%, while the front side illumination (FSI-CMOS) slightly mismatched the simulations, with an error margin of 14%. We also found that the full-screen saturation threshold for the BSI-CMOS was 25% higher than the FSI-CMOS. Our work demonstrates the applicability of the Fresnel diffraction model for BSI-CMOS, which provides a valuable reference for studying laser dazzling.

Synthesis, characterization and photoelectrochemical performance of Bi2Fe4O9 thin films

Mullite-type Bi2Fe4O9 has been little explored in thin film form as a photoanode for photoelectrochemical water splitting. In this study, Bi2Fe4O9 thin films have been prepared using the sol-gel technique from a simple precursor solution based on the corresponding metal salts, acetic acid, and polyvinyl alcohol. The films were deposited by dip-coating onto fluorine-doped tin oxide substrates and dried at 350 °C, repeating the dipping-drying cycle six times, and finally sintered at 600 °C. The films were characterized by GIXRD, revealing the formation of the material in its orthorhombic phase. Raman spectroscopy showed the Ag and B1g vibrational modes, validating the formation of the bismuth iron oxide. UV–Vis transmittance measurements revealed that the material exhibits two optical transitions: a direct band gap of 2.86 eV and an indirect band gap of 1.98 eV. FESEM micrographs and AFM images showed a uniform nanostructured surface morphology. The photoelectrochemical properties of the Bi2Fe4O9 films were studied using cyclic voltammetry and chronoamperometry with front side illumination, demonstrating the stability of the material in aqueous media and the generation of photocurrent in the presence of H2O2. Furthermore, results from intensity-modulated photocurrent spectroscopy (IMPS) revealed that the photocurrent is limited by both bulk and surface recombination and a short hole diffusion length.

Photocatalytic oxidation of n-decane in a NETmix photoreactor: Insights into the reactor geometry and illumination mechanism

This study focuses on the gas-phase photocatalytic degradation of n-decane using a NETmix photoreactor illuminated by UVA light-emitting diodes. The photoreactor is a static mixer composed of a network of cylindrical chambers interconnected by prismatic channels imprinted in a stainless-steel slab sealed with a borosilicate glass slab (reactor window with 55.7 cm2 of illuminated area). Photocatalytic performance was evaluated as a function of the flow rate (0.67 to 15 L min−1), corresponding to Reynolds number (Re) from 54 to 1209, using NETmix plates with 1 mm (92.3 cm2) and 3 mm depth (165.4 cm2), under back-side (BSI) and front-side (FSI) illumination mechanisms. The TiO2-P25 loading over the borosilicate slab (25–100 mg; BSI optimal: 75 mg) and stainless-steel slabs (100–400 mg; FSI-1/FSI-3 optimal: 200/400 mg) was optimized. Within system constraints, higher Re corresponds to increased reaction rate, apparent quantum yield, and reactivity, with decreased degradation efficiency, due to a reduction in the residence time, regardless of the reactor geometry and illumination. Moreover, operating at the same Re, the NETmix plate with 3 mm depth achieves reaction rates 2.2-/1.9-fold higher than 1 mm, considering FSI/BSI mechanisms. The results were consistent with applied experimental conditions and ray tracing simulations, indicating superior kinetic performance with higher catalyst superficial area. Ray tracing was coupled with Computational Fluid Dynamics (CFD) simulations to evaluate n-decane single-pass oxidation. A 94 % n-decane maximum experimental conversion was attained for a Re of 54, representing an error of ∼ 6.6 % compared to CFD simulation. In these conditions, only 1 % of n-decane was not mineralized, being identified aldehydes, alkanes, carboxylic acids, and ketones as the main reaction by-products. The influence of relative humidity (2 %-40 %) and n-decane inlet concentration (15–114 ppm) were also investigated.

Effects of Al2O3 Rear Interface Passivation on the Performance of Bifacial Kesterite‐Based Solar Cells with Fluorine‐Doped Tin Dioxide Back Contact

Herein, ultrathin Al2O3 is investigated as a rear interface passivation layer for kesterite solar cells with F:SnO2 (FTO) back contact for potential performance improvement. On the passivation layer, a thin Mo layer is deposited to improve the FTO's ohmicity. Further, NaF is evaporated on the copper zinc tin sulfide (CZTS) precursors to create openings at the passivation layer and achieve Na‐induced benefits in the absorber. The CZTS absorbers deposited directly on the Al2O3‐coated FTO peel off, while those with Mo interlayer do not. For pure sulfide kesterite devices, the Al2O3 layer reduces the short‐circuit current density (JSC), resulting in poor device efficiency. On the other hand, significantly higher JSC is realized for mixed sulfide and selenide kesterite devices with Al2O3 passivation layer, with the current density–voltage curve suggesting a reduced barrier height at the rear interface. As a result, the efficiency is improved from 1.5% for devices without Al2O3 to 4.6% for those with Al2O3. Likewise, improved external quantum efficiency response is observed in the devices with passivation layer for backside and frontside illumination. Therefore, contribution of Al2O3 passivation layer to the performance of kesterite‐based solar cells is evident from the results of this study.

Shallow Trench Isolation Patterning to Improve Photon Detection Probability of Single-Photon Avalanche Diodes Integrated in FD-SOI CMOS Technology

The integration of Single-Photon Avalanche Diodes (SPADs) in CMOS Fully Depleted Silicon-On-Insulator (FD-SOI) technology under a buried oxide (BOX) layer and a silicon film containing transistors makes it possible to realize a 3D SPAD at the chip level. In our study, a nanostructurated layer created by an optimized arrangement of Shallow Trench Isolation (STI) above the photosensitive zone generates constructive interferences and consequently an increase in the light sensitivity in the frontside illumination. A simulation methodology is presented that couples electrical and optical data in order to optimize the STI trenches (size and period) and to estimate the Photon Detection Probability (PDP) gain. Then, a test chip was designed, manufactured, and characterized, demonstrating the PDP improvement due to the STI nanostructuring while maintaining a comparable Dark Count Rate (DCR).

CIGS bifacial solar cells with novel rear architectures: Simulation point of view and the creation of a digital twin

The performance of bifacial Cu(In,Ga)Se2 (CIGS) cells does not yet reach the one of monofacial cells, with standard Mo rear contacts. By exploring optoelectronic simulations, this study addresses the impact of a transparent conducting oxide layer used as rear contact in CIGS solar cells. These simulations, which aim to create a digital twin of bifacial CIGS solar cells, offer insight into the impact of novel rear contact architectures. It was observed that with an indium tin oxide (ITO) rear contact the CIGS cell performance lacks in comparison to a Mo one due to an electrical barrier, under rear side illumination these devices may only reach 3.9 % in conversion efficiency. The implementation of dielectric rear passivation schemes have great performance benefits in cells with Mo rear contacts. Therefore, the same passivation strategy in ITO contacts is discussed and additional novel architectures are proposed, from which a design of alternated lines between dielectric and 15 nm Mo layers on ITO showed promising results. Such rear architectures aim to achieve i) a highly transparent rear contact, ii) an ohmic-like behaviour with CIGS, and iii) a low defective interface with rear passivation. The selenization of the complete 15 nm Mo in the proposed novel architecture during the CIGS growth was considered, resulting in transmittance values above 70 % and, notably, reaching the transparency of bare ITO in the infrared range. Such rear architecture may provide for bifacial CIGS solar cells with conversion efficiency values surpassing 20 and 15 % for front and rear side illumination, respectively, allowing to fully exploit bifaciality.

Enhanced performance of Cu2ZnSnS4 based bifacial solar cells with FTO and W/FTO back contacts through absorber air annealing and Na incorporation

This study reports on the influence of air annealing and Na incorporation into the absorber on the performance of Cu2ZnSnS4 (CZTS) bifacial solar cells with FTO and W/FTO back contacts. Na was incorporated by depositing ∼12 nm thick NaF on the CZTS precursors prior to the sulfurization process via thermal evaporation. After sulfurization, some of the samples were annealed in air at 300 °C for 90 s and subsequently at 200 °C for 600 s. Transmission electron microscopy confirmed sulfurization of the W interlayer to form WS2 which improves the FTO ohmicity. Na incorporation improved grain size of the absorber as revealed by scanning electron microscopy. Non-annealed samples had the unwanted SnS2 phase while the air annealed samples, particularly those with both W interlayer and Na incorporation, were exempt from SnS2 phase, as was confirmed through grazing incident X-ray diffraction and Raman spectroscopy. These results suggest that absorber air annealing and Na incorporation enhance absorber crystal growth which is advantageous in reducing bulk carrier recombination. As a result, the efficiency was significantly improved from 3.0% for solar cells fabricated directly on FTO to 5.2% for those whose absorbers were air annealed, incorporated with Na and made on W/FTO. The latter also exhibits the highest external quantum efficiency response and calculated short circuit current density for both sides illumination. This indicates that the air annealing, Na incorporation and W interlayer are enhancing the performance of bifacial CZTS solar cells with FTO back contact for both back side and front side illumination.

Optimization of bifacial Ge-incorporated Sb2Se3 thin-film solar cells by modeling Cu2O back buffer layer

We have investigated bifacial Ge-incorporated Sb2Se3 thin-film solar cells by modeling and simulating a back buffer layer including Cu2O to optimize the bifacial device performance. A Ge-incorporated Sb2Se3 absorber layer was grown using Vapor Transport Deposition to extract the input parameters for the simulation, followed by exploring the properties of the transparent back buffer layer. After selecting a Cu2O back buffer layer, we conducted the optimization study of bifacial Ge-doped Sb2Se3 devices by varying a set of devices and materials parameters. The optical bandgap is characterized as 1.23 eV for Ge-incorporated Sb2Se3 absorber and the absorption coefficient is 3 × 105 cm−1 at 600 nm. Using these input parameters, we simulated the device configuration of ZnO:Al/i-ZnO/CdS/Ge-Sb2Se3/back buffer layer/transparent conductive oxide. Firstly, we checked the impact of conduction and valence band offsets on device performance, indicating the valence band offset of the back buffer layer plays a significant role. In particular, zero or small positive valence band offset minimizes a Schottky hole barrier, which could reduce hole current clamping near the back buffer region. As for back buffer doping concentration, high back buffer doping concentration (1 × 1015 cm−3 or higher) is required to improve device performance even with zero valence band offset, whereas low absorber doping concentration (<1 × 1014 cm−3) enables higher efficiency due to the enlarged energy band bending. For bifacial device performance, a Cu2O back buffer layer is simulated by varying critical input parameters such as absorber thickness, doping concentration, and defect concentration near the back buffer interface. The best efficiency of front-side illumination is 19.7%, Voc (744.4 mV), Jsc (40.14 mA/cm2), and FF (66.1%) and that of the rear-side illumination is 13.0%, Voc (724.5 mV), Jsc (31.6 mA/cm2), and FF (56.7%). Consequently, the bifaciality factor is 66%.

Enhanced solar hydrogen production by manipulating the spatial distribution of Pt catalyst onto Si micro-pyramid arrays

Monolithic integrated photoelectrochemical devices consisting of semiconductors and co-catalysts have always been restricted by the trade-off between light absorption and catalytic activity upon frontside illumination. Herein, we proposed a facile strategy to spatio-selectively deposit Pt catalyst on the top of p-Si micro-pyramids, which not only enables substantial light absorption but also immensely boosts the charge transport and mass transfer. With the help of dark-field microscopy and microscopic photocurrent mapping, it is revealed that the top of p-Si micro-pyramids is an ideal electron-migration channel for efficient charge carrier extraction. This spatio-selective strategy affords the Si photocathode to achieve a high applied bias photon-to-current efficiency of 3.84% for hydrogen production, significantly greater than the control sample with the same amount of Pt catalyst deposited uniformly on the same substrates (0.04%).

The Influence of Preparation Parameters on Structural and Optical Properties of N-Type Porous Silicon

In this paper, we describe the formation of macroporous silicon (MPS) formed anodically polarized on n type Si (100) substrates at a constant current density under front side illumination using two electrolytes, HF/Ethanol and HF/Ethanol/H2O2. The effect of adding H2O2 in the solution on the resulting pores were investigated by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), contact angle measurements and UV-vis spectrophotometry. The results showed that for the anodization conditions the MPS formed in peroxide based (H2O2)/HF/Ethanol solution exhibited structures with larger pore size and different pore morphologies depending on the etching time than those formed in HF/Ethanol. The pore density and the pore size of the MPS samples increased with the etching time. The infrared absorption spectrum (FTIR) carried out on the freshly prepared sample indicates that the MPS contains Si-Hx bonds which decrease with increasing the etching time. Finally, measurements of contact angle indicate that the formed MPS samples are highly hydrophobic.

Accurate Prediction of Photon Detection Probability Based on the 2-D Dead-Space Model for SPADs

In this article, we propose an accurate procedure for predicting the photon detection probability (PDP) for single-photon avalanche diodes (SPADs). The energy threshold needed for triggering impact ionization, that is, the dead space, was carefully considered and developed into a 2-D solution. The input parameters are based on the manufacturing process and device layout. The breakdown probability of each point on the 2-D profile was calculated without adding fitting parameters, which can overcome the inaccurate prediction caused by the uneven distribution of the electric field and photon generation for the device with the guard ring. Two sets of SPADs based on 180 nm for front-side illumination and 55 nm for back-side illumination were fabricated and tested. The simulation and experimental results are in accordance with each other. This procedure makes it very easy to optimize the device structure based on the simulation results. In addition, the invention can invoke graphics processing units (GPUs) in the MATLAB platform to perform parallel acceleration calculations and improve the calculation efficiency.

Size- and facet-dependent photoelectrochemical properties of Cu2O crystals

While Cu2O cubes show the best photon-to-current efficiency under front-side illumination, photocurrent is greatly enhanced for rhombic dodecahedra under back-side illumination with more facile charge transport.

Schottky barrier contact on In0.53Ga0.47As with short-wave infrared transparent conductive oxide

In this study, we fabricate and investigate Schottky barrier contact on n- and p-type In0.53Ga0.47As with transparent conductive oxide (TCO) that transmits light from the visible to short-wave infrared (SWIR) region. The TCO/p-In0.53Ga0.47As contact exhibits explicit rectifying behavior in current–voltage measurement, with an effective Schottky barrier height of 0.587 eV (I–V) and 0.567 eV (C–V). Conversely, the TCO/n-In0.53Ga0.47As exhibits the Ohmic behavior. From high-resolution transmission electron microscopy observations, we identified two types of interfacial layers between TCO and InGaAs: an In/Ga-rich InGaAs oxide layer and an In/Ga-deficient InGaAs layer. These interfacial layers may have a significant impact on the performance of the Schottky barrier contact. An ultra-thin Ni-layer insertion at the TCO/n+-InGaAs interface reduces the contact resistivity by more than an order of magnitude while maintaining high transparency. The TCO/p-InGaAs Schottky barrier contact also performs broadband light detection from the visible to SWIR region in a front-side illumination manner, which is highly promising for detecting wavelengths covering the optical communication band.

M1-xSb1-ySδ (M = Ni, Cu, Co) ternary metal sulfides: Emerging candidates for [formula omitted] reduction in bifacial dye-sensitized solar cells

Antimony-based ternary metal sulfides such as Ni9Sb2S8, Cu3SbS3, and CoSbS have been used as counter electrodes (CEs) in bifacial Dye-Sensitized Solar Cells (DSSCs). The electrochemical results show that antimony-based ternary sulfides have the highest peak current density (JPC), lower peak-to-peak separation (EPP) and charge transfer resistance (RCT) than the corresponding binary sulfides. Notably, under front-side illumination, the highest short circuit current (JSC) of 10.19 mA cm−2 is reached for Cu3SbS3, 9.77 mA cm−2 for Ni9Sb2S8 and 10.44 mA cm−2 for CoSbS, all of them are greater than Pt CE. The efficiency of the CoSbS CE is ∼ 97%, Ni9Sb2S8 CE is ∼ 84% and Cu3SbS3 CE is ∼ 66% when normalized with the efficiency of the Pt CE (∼5.54%). The performance of these ternary sulfide CEs is also evaluated for rear-side illumination. This report elucidates the new class of materials that might be used as a potential counter electrode for bifacial DSSCs.

Photoelectrochemical degradation of selected organic substances on Fe2O3 photoanodes: a comparison with TiO2.

The photoelectrochemical degradation of selected aromatic substances, acid orange 7 (AO7), salicylic acid (SA), benzoic acid (BA), and 4-chlorophenol (4-CP) was studied on hematite (α-Fe2O3) and compared with titanium dioxide (TiO2), both deposited as thin films on conducting substrates (FTO/glass). Batch type reactors were used under backside and front side illumination. Electrical bias was applied on the semiconducting electrodes, such that only valence band processes leading to oxidative pathways were followed. The initial Faradaic efficiency, f0, of degradation processes was determined from the UV-Vis absorbance decrease of the starting materials. f0 for 1mM AO7 degradation in 0.01M sulphuric acid was found to be 7.5%. When the pH of the solution was neutral (pH 7.2) or alkaline (pH 13), f0 decreased to 1.7%. For 1mM SA, f0 was 6.2% on hematite photoanodes and 6.1% on titanium dioxide. For 1mM benzoic acid and 4-chlorophenol, f0 was an order of magnitude lower, but only on hematite. This is ascribed to the lack of OH· radical formation on hematite, which seems to be essential for the photooxidation of these compounds.

A Low-Power Indirect Time-of-Flight CMOS Image Sensor With Fixed Depth Noise Compensation and Dual-Mode Imaging for Depth Dynamic Range Enhancement

We present a low-power indirect time-of-flight (iTOF) image sensor with fixed depth noise compensation and dual-mode imaging for depth dynamic range (DDR) enhancement. To reduce the power consumption from high-frequency pixel modulation, a TX driver with a single-sided clock chain is employed in the sensor. The inherent phase delay of the clock chain and the delay of the row bus are measured using row-parallel and column-parallel time-to-digital converters (TDCs) to compensate for the column and row fixed depth noise (FDN). To achieve a wide depth dynamic range (WDDR), the reconfigurable pixels and column circuits support dual-mode: short-range (SR) and long-range (LR) modes. A WDDR image is generated in a single frame through the mixed reconfiguration of the pixel array and interpolation. In addition, the temporal noise is suppressed without a significant time budget through a fast multiple sampling (FMS) scheme with 10b successive approximation register (SAR) analog-to-digital (ADCs). A prototype iTOF image sensor was fabricated using a 110 nm frontside illumination (FSI) CMOS image sensor (CIS) process and fully characterized. The sensor achieved a DDR of 4 m (0.7 to 4.7 m) with less than 1.7% nonlinearity and 0.9% depth noise. The FDN was suppressed to less than 2.1 cm at a low power consumption below 70 mW through the proposed compensation scheme using row and column TDCs. The temporal noise was only 0.48 mV <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathbf {rms}}$ </tex-math></inline-formula> owing to the FMS.

Transparent Conductive Oxide (TCO) Gated Ingaas Mosfets for Front-Side Illuminated Short-Wave Infrared Detection

TCO gated InGaAs MOSFETs are demonstrated as a high responsivity and broadband short-wave infrared (SWIR) photodetector under front-side illumination (FSI). InGaAs MOSFET structures have many advantages for monolithic integration with optical communication devices with O, C, and L bands and Si-LSI.The TCO gated InGaAs MOSFETs were fabricated through the gate-last method as shown in Fig. (a) [1]. A 300-nm-thick p-type In0.53Ga0.47As layer was grown on an InP (001) wafer using MOCVD. After the deposition of a 10-nm-thick Al2O3 protection layer by ALD, the InGaAs active region was defined by chemical wet etching for mesa isolation. For the formation of the source/drain region, Si ions were implanted with 2×1014 cm-2 at 15 keV, followed by RTA at 450 °C for 10 min to achieve dopant activation. After splitting the Al2O3 protection layer, a 10-nm-thick Al2O3 gate oxide layer was deposited again. As TCO gate, Ce and H co-doped In2O3 (In2O3: Ce, H) with an electron mobility of ~160 cm2/V·s and a carrier density of ~ 2×1020 cm-3 were used [2, 3]. The amorphous TCO gate, which were deposited onto the Al2O3 layer using the ion plating method, were lifted off and crystallized by annealing at 250 °C for 30 min. Finally, Ti/Au formed for the S/D and gate contact after post-metallization annealing (PMA) at 250 °C for 30 min.The thin TCO films exhibited a very low specific contact resistance of 9.01 × 10-8 W·cm2 and a sheet resistance of 18.7W/sq. We confirmed the normal n-channel MOSFET operation with an I on/I off ratio of > 1×104. S.S. and D it values were 134 mV/dec. and 5.2 × 1012 eV-1cm-2, respectively. The peak G m was observed at V G= 0.5 V, and the extracted peak field-effect mobility was 620 cm2/V·s. The threshold voltage negatively shifted to -0.38 V, operating in enhancement mode owing to the work function of the TCO (4.2 eV), which is smaller than the Fermi level energy of p-type InGaAs (5.09 eV).Figure (b) shows the I D - V G characteristics of InGaAs MOSFETs at V G = 1 V in the dark and under illumination at the excitation wavelength of 1550 nm with an incident optical power of 5213 nW. SWIR light was illuminated in the channel area (L/W = 10 μm/10 μm) of TCO gated InGaAs MOSFET with a spot size of 10 μm. Under SWIR illumination, an increase in can be observed in the entire gate bias. Owing to the normally-on operation of the TCO gated InGaAs MOSFET, a photocurrent is detected even if the gate bias is 0 V. The photocurrent increased with the gate bias and reached the maximum in the vicinity of V G = 0.5 V, which corresponds to that of the maximum transconductance. The primary photo-response when the device is under illumination is known as the photovoltaic effect [4, 5]. The photo-generated holes move to the source region and accumulate at the potential barrier between the source and the channel. This results in the effective reduction of a potential barrier for electrons at the source edge. These phenomena lead to a decline in the threshold voltage of the MOSFET, which leads to the increase of the drain current. The threshold voltage of the TCO gated InGaAs MOSFETs in the dark was -0.35 V, and this value shifted to -0.45 V under illumination. Because is proportional to the mobility at the MOS interface, the improvement of the interface quality of the TCO/Al2O3/InGaAs MOS structures can enhance the sensitivity.Owing to the SWIR transparent TCO, we observed a responsivity of more than 1 A/W in the range of 1000 nm to 1800 nm, which includes the entire optical communication wavelength bands (1260–1625 nm). Because the maximum sensitivity of InGaAs photodiode was approximately 1 A/W at approximately 1550 nm [6], it is demonstrated that TCO gated InGaAs MOSFETs is a highly sensitive device in the SWIR region owing to the gain mechanism in the photoFETs.[1] T. Maeda, et al., Appl. Phys. Lett., 119, 192101 (2021).[2] T. Koida, et al., Status Solidi A, 215, 1700506 (2018).[3] T. Koida, et al., Status Solidi A, 218, 2000487 (2021).[5] Y. Takanashi, et al., IEEE Electro. Dev. Lett., 19, 472 (1998).[6] http://www.thorlabs.com. Figure 1

Wireless Anti-Stokes Photoinduced Electrochemiluminescence at Closed Semiconducting Bipolar Electrodes.

Wireless electrochemical systems constitute a rapidly developing field. Herein, photoinduced electrochemiluminescence (PECL) is studied at Si-based closed bipolar electrodes (BPEs) for designing anti-Stokes systems that can convert IR into visible photons, without direct electrical contact. We show that protection of the anodic emitting pole of the BPE allows the triggering of bright and longstanding emission under the synergetic actions of an external bias and IR illumination. Photoactive n- and p-type Si BPEs are studied with front-side and back-side illumination, respectively, and nonphotoactive n+-Si BPEs are studied in the dark. Two electrochemiluminescent (ECL) systems ([Ru(bpy)3]2+/TPrA and L-012) are tested, and we show that the onset bias and the anti-Stokes shift can be controlled by the ECL system that is employed. These advances, rationalized by simulations, will be useful for the design of original PECL systems for chemical sensing or photodetection.